Question

GAnswer the following in brief.
1. Give two examples of desirable chemical changes.
2. List the conditions necessary for rusting.
3. Write three methods which can be used to prevent rusting
4. How will you prove that dissolution of salt in water is a physical change?​

Answer 1

Answer:

a chemical change results from a chemical reaction while or physical change is when matter change from but not chemical identity for example cooking, rusting.

2) air and moisture are necessary for rusting of iron .

3) use of oil or grease significantly reduces the changes of developing rust in iron basically oil or grease for a protective layer over iron just as paint does and their for their from prevent rust formation.

4) dissolving a solid in liquid such as table salt in water is a physical change because only the state of the matter has changed the physical change can often be received along the water of evaporate combined with the water to causea chemical reaction .